Relationship between Inflammatory Stimulation and Cell Biomechanics in Intervertebral Disc Degeneration

Intervertebral disc (IVD) degeneration (DD) affects over 40% of adults, is a leading cause of disability and costs over $100 billion in economic burden annually. DD is a multifactorial process ultimately leading to tissue breakdown and loss of functionality. DD is associated with increased levels of pro-inflammatory cytokines within the disc and the catabolic effect of inflammatory stimulation on disc cell biology has been well studied. As part of its physiological functioning the disc experiences mechanical, hydrostatic, and osmotic stimuli. Cells within the disc are mechanosensitive to these signals, where hyper physiological and damaging physical signals can perpetuate degenerative effects in the disc. Despite the known contributions of inflammatory stimulation and biomechanics to DD individually, the interaction of inflammation and biomechanics in the IVD is still not well understood. The objective of this thesis is to examine the role of inflammatory stimulation on cellular biophysical properties in the disc, subsequent implications at the tissue level, and its contributions to DD. Here the cell cytoskeleton and actomyosin contractility are identified as key regulators of the response of cellular properties to inflammation. Actomyosin contractility is further identified as a regulator of well-known biological responses to inflammatory stimulation within the disc including ECM catabolism and altered disc tissue mechanics. Altered cellular biophysical properties observed in clinical human DD samples indicate the inflammatory milieu present in DD drive changes in cellular mechanics. Increasing actomyosin contractility is shown to be effective in mitigating the effects of inflammation on cellular biophysical properties and subsequent degenerative effects highlighting its potential as a therapeutic for the treatment of DD.